One of the most common bacterial infections is that of the urinary tract. Patients who need rapid diagnosis of urinary tract infections (UTIs) include premature newborn infants, prepubertal girls and young boys, sexually active women, elderly males and females, pre-operative patients, patients with chronic disease, patients with neurological disorders, patients with genitourinary congenital disorders including urethral valves and reflux, patients with sickle cell disease, patients with renal disease and polycystic kidney disease, patients having undergone renal transplantation and pregnant patients. The diagnosis of UTI in the elderly and in infants, in particular, is difficult because of different signs and symptoms and the inability to communicate.
One technique for diagnosing UTI involves measuring the level of nitrites in urine. In particular, many bacteria, such as E. coli (the most common bacterium causing urinary tract infection), contain an enzyme that reduces nitrate ions (NO3−) to nitrite ions (NO2−). Vesical urine of most healthy persons is free from bacteria and as such, the detection of nitrite in urine may be used to help diagnose urinary tract infection. Several methods have been developed for assessment of nitrites. For example, dipsticks based on detection of nitrites have been developed that contain an area predisposed with reagents. The test sample is spotted onto the area so that the nitrites react with the reagents, thereby inducing a color change. Unfortunately, such test methods generally require a controlled reading window. However, it is not always feasible to carefully monitor testing, particularly in consumer-based applications.
As such, a need currently exists for an improved technique for detecting an nitrites in a test sample.